Someone explain to me, Matt, if you could, why a firmware update would ever be needed to correct an IR problem. Now, IF and just IF the receiver can't remember its firmware, and needs a new installation of firmware which masquerades or might even be an update, then that makes sense.

Original Poster says Denon works with Denon remote. Thus the Denon is not the problem. Let me digress to HDMI for a moment: As Brent explained to me recently, sometimes Denons appear to have HDMI problems because they are built to handle EXACTLY the right HDMI signal, and when other components send sloppy HDMI, they won't pass it. Other AVR brands might work in these instances if they are NOT AS GOOD as the Denons and will let sloppy HDMI pass through...so, keeping in mind that a receiver so good that it squeaks when it walks might not be able to deal with wrong signals:

Did the Russound suddenly stop passing the IR signal properly? Well, then, how? Why? And how many IR receivers are there in the system -- is there a room where the lighting, or the bulbs, have changed and that room now has different lighting and an interfering IR signal from the lighting is passing through the Russound?